Difficult Functions Problem

[cbrombe1]

Hello All,

I'm struggling on this problem :

If n is an integer and f(n) = f(n – 1) – n, what is the value of f (4)?

(1) f(3) = 14

(2) f(6) = -1

FYI, answer is D. Please advise..thanks!

[mals24]

St 1: f(3)=14

f(4) = f(3)-4

= 14-4 = 10...SUFF

St 2: f(6) = -1

-1 = f(5)-6
f(5) = 5

f(5) = f(4)-5

5=f(4)-5
f(4) = 10....SUFF